Administering fluids containing medicine or nutrition on an ongoing basis in precise quantities to a patient is known. Typically, nutritional fluid is delivered to the patient by a pump set including a flexible elastomeric tubing loaded on a flow control apparatus, such as a peristaltic pump, which delivers fluid to the subject at a controlled rate of delivery. The peristaltic pump usually has a housing that includes a rotor driven by a motor through a gearbox. The rotor forces fluid through the flexible tubing of the pump set by the peristaltic action effected by reversible compression created by impingement, e.g., pinching, by one or more rollers mounted on the rotor. The pump set may have a valve mechanism for selectively permitting or preventing fluid flow communication through the pump set. A controller may operatively regulate the motor which effectively controls fluid flow.
Existing flow control apparatus are capable of monitoring rotation of the rotor using an encoder on the rotor. The rotation speed of the rotor can be used to determine a flow rate of the nutritional fluid being delivered through the apparatus.
Flow control apparatus may also be capable of monitoring and detecting fluid flow conditions that can occur within the loaded pump set during operation of the flow control apparatus. One such flow condition is an occlusion in the pump set. The presence of an occlusion prevents nutritional liquid from being delivered to the patient and can damage the pump set and flow control apparatus. A normal flow condition exists when there is no flow condition that would occlude or obstruct fluid flow in the pump set. However, when viscous nutritional fluids are used, pressure in the pump set may increase during otherwise normal flow conditions. Thus, if pressure is exclusively used to detect an occlusion, a normal flow condition can appear to be an abnormal flow condition when a viscous fluid is used with the pump set.